d663: 11730 - Number Transformation
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Accepted rate : 101人/148人 ( 68% ) [非即時]
評分方式:
Tolerant

最近更新 : 2010-03-23 14:38

Content

You are given an integer number S. You can transform any integer number A to another integer number B by adding x to A. This x is an integer number which is a prime factor of A (Please note that 1 and A are not being considered as a factor of A). Now, your task is to find the minimum number of transformations required to transform S to another integer number T.

給你一個數字S,你可以將A轉換成B藉由加上一個X,X是一個A的質因數(1跟A不考慮進去),現在你的工作就是找出最少需要轉換次數把S轉換成T

EX: 6 12

6->9->12   2次

6->8-> 10->12 3次

Input

For each test case, there will be a line with two integers, S (1<=S<=100) & T (1<=T<=1000), as described above. The last test case will be followed by a line with two 0 s denoting end of output. This case should not be processed.

每組測資都有兩的數字S (1<=S<=100) & T (1<=T<=1000),

兩個0代表結束,不用輸出任何數字 。

Output

For every test case except the last one, print a line of the form “Case X: Y” where X is the serial number of output (starting from 1). Y is the minimum number of transformations required to transform S to T. If it is not possible to make T from S with the given rules, Y shall be -1.

對於每個一個測資,除了0 0以外 ,請應出 “Case X: Y”,X從1開始算起,Y為S轉換到T的最小次數,若是無法轉換成功請書出-1

Sample Input
6 12
6 13
0 0
Sample Output
Case 1: 2
Case 2: -1
測資資訊:
記憶體限制: 512 MB
公開 測資點#0 (100%): 3.0s , <1M
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出處:
UVa11730 [管理者:
snail (蝸牛)
]


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